The invention relates to an apparatus for destroying calculi in body cavities with the aid of an ultrasonic transducer as vibration generator.
From German OS No. 20 53 982, an apparatus for destroying stones in the urinary bladder, in the ureter, in the kidney, and the like, is already known, in which the sonic energy of an ultrasonic transducer is employed in order to set a work attachment at the tip of a probe into longitudinal vibrations. The work attachment then breaks up the stone. Such an apparatus, however, is technically quite complicated; it is semi-invasive and also not very accurate in aiming in application. From U.S. Pat. No. 3,237,623, in conjunction with the destruction of cells of a cell group in the eye or brain, yet another apparatus, which operates with an ultrasonic transducer as excitation vibrator, is known. In the case of this apparatus, however, with the aid of the ultrasound, punctiform fields of higher temperature are produced by means of which then the respective cell group is destroyed. In the case of apparatus of this type, the energy density is too low to be able to destroy calculi such as stone, or the like. The above-cited apparatus which operate with ultrasound are thus poorly suited for destroying calculi specifically in body cavities. For this reason, in practice, up to the present time only such apparatus have been employed which do not function on the basis of ultrasonic excitation. These apparatus relate to shock wave generators with a focusing chamber wherein at the focal point of a water-filled revolution ellipsoid there is disposed a spark discharge path which, in the case of electric ignition through spark discharge, generates a shock wave. The shock wave is transmitted via a coupling membrane to the body of the patient; it thus reaches the calculus which, due to a corresponding previous adjustment of the focusing chamber, is disposed at the second focal spot of the revolution ellipsoid. Apparatus of this type are, for example, prior-known from German Pat. No. 22 23 319 and German Pat. No. 23 51 247. Spark discharges require high sparking voltages in the range of between 15 to 30 kV. However, these high sparking voltages raise problems regarding a satisfactory insulation with respect to the patient. Moreover, spark discharges always lead to burning loss. This requires constant maintenance, and the number as well as frequency of ignitions (which are necessary for a treatment) is limited.